Per Ron's message below, you can also download the free software AppCAD from
HP...

It has an impedance calculator for the various transmission line structures (or
passive circuits), including coplanar waveguide (with & without ground plane).
It's very useful if you want a first pass look at the impedance of any line.

The signal with grounds either side is referred to as co-planar waveguide in
microwave terms and there are many simulators for that impedance. Try the
IEEE MTT Proceedings for papers on the subject. If you want a tool that
can simulate it RF Design Magazine has a series of software routines donated
from many
engineers over the years. If you want a commercial tool to simulate it Try
HPEEsof
Touchstone, which used to cost about $500 for a dos version and more for windows
versions.

In the case of a signal with a ground on only one side I would look for an
offset
coplanar waveguide model and extend the unused groundplane to the limits of the
model.

Ron MIller

CAI ZhongPing wrote:

> Dear experts,>> Sorry to disturb you again. :) The following figure explains the case more
clearly:>> ________ ________ ________ ________> |________| |________| |________| |________|> GND Signal GND Signal>> So they are not driven differentially. General tools calculate differential
impedance, right? Can just setting the distance to the plane very high get
correct result?>> Thanks for your help and look forward to your reply.>> Cai>> **** To unsubscribe from si-list: send e-mail to majordomo@silab.eng.sun.com.
In the BODY of message put: UNSUBSCRIBE si-list, for more help, put HELP.
si-list archives are accessible at http://www.qsl.net/wb6tpu/si-list ****

The signal with grounds either side is referred to as co-planar waveguide
in
microwave terms and there are many simulators for that impedance.
Try the
IEEE MTT Proceedings for papers on the subject. If you want a
tool that
can simulate it RF Design Magazine has a series of software routines
donated from many
engineers over the years. If you want a commercial tool to simulate
it Try HPEEsof
Touchstone, which used to cost about $500 for a dos version and more
for windows
versions.

In the case of a signal with a ground on only one side I would look
for an offset
coplanar waveguide model and extend the unused groundplane to the limits
of the
model.

Ron MIller

CAI ZhongPing wrote:

Dear experts,

Sorry to disturb you again. :) The following figure explains the
case more clearly:

So they are not driven differentially. General tools calculate differential
impedance, right? Can just setting the distance to the plane very high
get correct result?

Thanks for your help and look forward to your reply.

Cai

**** To unsubscribe from si-list: send e-mail to majordomo@silab.eng.sun.com.
In the BODY of message put: UNSUBSCRIBE si-list, for more help, put HELP.
si-list archives are accessible at http://www.qsl.net/wb6tpu/si-list
****

**** To unsubscribe from si-list: send e-mail to majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE si-list, for more help, put HELP. si-list archives are accessible at http://www.qsl.net/wb6tpu/si-list ****